Imagine bacteria, fitted with artificial DNA, harnessed to churn out an anti-malaria vaccine - that is happening already in California.

Or imagine bacteria with synthetic genes that make them light up when parasites are detected in drinking water - that has been proven to work at Imperial.

Or imagine organisms transformed into factories to make us fuel or materials, or engineered to gobble up oil spills and industrial pollution, or crafted to provide the power and wiring for the next generation of computers.

Some of this happening now, but much more may also be possible in the future.

New life forms

When I asked one leading scientist where this could lead, he replied impatiently: "That's like wondering what a computer could do back in the 1960s - who can tell?"

But the concept of synthetic biology does take some getting used to - not just the very idea of creating new life-forms and the scale of the economic potential but also of course the implications, which are profound and, to some, very worrying.

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Media captionThe BBC's David Shukman reports on "synthetic biology"

Ultimately, this is about taking control of nature, redesigning it and rebuilding it to perform some task.

No wonder the phrase "playing God" comes up in almost every conversation. With it comes a grand historical vision.

If the 19th Century was all about the revolution of harnessing energy from fossil fuels, and the 20th Century was about exploiting the power of data, this century will be about controlling biology.

So how does one understand this brave new world?

The starting point is GM or genetic modification, the technology, with us for several decades, in which the genes of one organism are inserted into another.

Over recent years, GM has led to crops that are resistant to weed killers or insecticides.

Most recently, researchers have been shuffling genes to give ordinary oranges the health benefits of blood oranges or white rice the same nutritional value as whole rice.

Most startling are the goats that carry the spider gene that produces silk, as featured by Adam Rutherford in his recent Horizon.

Hostile response

In Europe, this kind of work has often been regarded with suspicion, even hostility.

Trial crops have been attacked and the major supermarket chains in Britain, fearful of public nervousness, do not stock GM food.

What makes this possible is a rather sobering fact: that DNA, the twisting strands that hold the genes of every living thing on Earth, essentially comes down to four basic molecules.

But what is coming next with synthetic biology takes this research into an entirely different league, and only now is it entering the public consciousness.

The basic principle is that nature is treated like engineering. It is just a set of building blocks, and genes are mere components.

And just as with building a car or a plane, the different parts can be designed and assembled any way you want.

So instead of taking the genes of one organism and adding them to another, scientists dream up new genes, select their characteristics, get them made up artificially and then put them to use.

What makes this possible is a rather sobering fact: that DNA, the twisting strands that hold the genes of every living thing on Earth, essentially comes down to four basic molecules.

These are adenine, cytosine, guanine and thymine, better known by their first letters A, C, G and T.

And because these molecules are well understood, they can be manufactured synthetically.

Here is how it works. A scientist wants to get an organism to do a particular function.

They sit down at their computer and manipulate the patterns of the four molecules to design the genes that will make that function happen.

They then send off an order to a specialist "gene synthesiser"- yes, such companies now exist. Imperial College uses a firm in Germany.

They make up the new genes and send them back in the post - a tiny vial containing an artificially-made code for life.

Surge of new thinking

The synthetic genes are then inserted into a bacterium which has had its own original DNA stripped out.

The organism will do exactly what the scientist intended: a living thing, but under the control of Man.

That makes it sound too easy. This science is in its earliest days. But it is fostering a surge of new thinking and new approaches.

I wonder if the dawn of the nuclear age had the same kind of feel, with science taking us to the brink of an unparalleled new power

The largest of the synthetic biology labs in Britain is at Imperial College.

The likeliest of its products will be sensors, half-electronic half-biological devices that harness engineered bacteria to light up when parasites or infections are detected.